Automated equipment is typically employed in industry to process, print, and/or sort sheet material for use in manufacture, fabrication and mail-stream operations. One such device associated with some embodiments described herein is directed is a mail-piece sorter which sorts mail into various sortation bins or trays for delivery.
Mail-piece sorters are often employed by service providers, including delivery agents, e.g., the United States Postal Service (“USPS”), entities which specialize in mail-piece fabrication, and/or companies providing sortation services in accordance with the Mail-piece Manifest System (“MMS”). Regarding the latter, most postal authorities offer large discounts to mailers willing to organize/group mail into batches or trays having a common destination. Typically, discounts are available for batches/trays containing a minimum of two hundred (200) or so mail-pieces.
The sorting equipment organizes large quantities of mail destined for delivery to a multiplicity of destinations, e.g., countries, regions, states, towns, and/or postal codes, into smaller, more manageable, trays or bins of mail for delivery to a common destination. For example, one sorting process may organize mail into bins corresponding to various regions of the U.S., e.g., northeast, southeast, mid-west, southwest and northwest regions, i.e., outbound mail. Subsequently, mail destined for each region may be sorted into bins corresponding to the various states of a particular region e.g., bins corresponding to New York, New Jersey, Pennsylvania, Connecticut, Massachusetts, Rhode Island, Vermont, New Hampshire and Maine, sometimes referred to as inbound mail. Yet another sort may organize the mail destined for a particular state into the various postal codes within the respective state, i.e., a sort to route or delivery sequence.
Note that a service provider might want to process a batch of mail-pieces of varying sizes. For example, a batch might include postcards, standard business envelopes, “full page” envelopes, etc. Typically, a singular tack kick on a tailing edge of a mail-piece might be used to prevent lead edge to trail edge collisions when stacking. This, however, might only be effective when processing mail-pieces of similar size. Moreover, sortation equipment has been made smaller to accommodate the physical limitations of available space, and throughput requirements continuously increase. As the throughput requirements increase, the speed of operation increases commensurately which can increase the frequency of jams or damage to mail-pieces as they are diverted from a high-speed feed path to one of the sortation bins. Damage can occur when a mail-piece comes to an abrupt stop, remains in contact with a high-speed belt or continuously operating roller, collides with a neighboring mail-piece, etc.
Various attempts have been made to control the divert/stacking function and configure the sortation bin such that a jams and damage are mitigated when a mail-piece is collected/accumulated in a sortation bin. In Stephens et al. U.S. Pat. No. 4,903,956, a divert/stacking assembly includes rotating arm which is driven about an axis which is substantially orthogonal to the feed path and in-plane with sheet material at it travels, on-edge, along the feed path. Once the leading edge of the sheet material comes to rest against a registration stop, the arm is activated to urge the trailing edge of the sheet material into the bin, thereby causing the edges of the accumulated sheets to be in register and each of the sheets to be parallel. While systems such as that described in the ″956, patent improve the general alignment of sheets within a sortation bin, such divert/stacking assemblies do not account for variable forces which may be required to divert such sheet material or sheet material which may vary in weight or thickness or size. Furthermore, as the rotating arms or urge rollers continue to operate, such divert/stacking assemblies can damage the sheet material.
A need, therefore, exists for a stacking assembly which aligns sheet material, e.g., mail-pieces of various sizes, in a sortation bin while mitigating jams and damage to the sheet material.